Ring-opening metathesis polymerization on well defined silica nanoparticles leading to hybrid core–shell particles

The grafting and catalytic activity of a metathesis catalyst on well defined silica nanoparticles is described. The aim of this was to test the catalysis properties of a ligand-linked catalyst in ring-opening metathesis polymerization and also the possibility to obtain controlled hybrid materials. This was carried out by reaction of a synthesized hydroxy functionalized phosphine Cy2P(CH2)10OH with Cl2Ru(PPh3)2(CH–Ph), leading to a metathesis catalyst bearing a hydroxy group at the end of a ligand. This group was reacted with well defined silica nanoparticles with a diameter of 200 nm, that had acyl chloride functions at their surface. The grafting density was calculated from thermogravimetry experiments and found to be around 7 µmol m–2. The activity of the catalyst was tested for the ring-opening polymerization of norbornene..

Electrodeposition of two-dimensional silver films under dihexadecyl phosphate monolayers

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Hybrid vesicles from lipids and block copolymers: phase behavior from the micro-to the nano-scale

International audienceIn recent years, there has been a growing interest in the formation of copolymers-lipids hybrid self-assemblies, which allow combining and improving the main features of pure lipids-based and copolymer-based systems known for their potential applications in the biomedical field. In this contribution we investigate the self-assembly behavior of dipalmitoylphosphatidylcholine (DPPC) mixed with poly(butadiene-b-ethyleneoxide) (PBD-PEO), both at the micro- and at the nano-length scale. Epifluorescence microscopy and Laser Scanning Confocal microscopy are employed to characterize the morphology of micron-sized hybrid vesicles. The presence of fluid-like inhomogeneities in their membrane has been evidenced in all the investigated range of compositions. Furthermore, a microfluidic set-up characterizes the mechanical properties of the prepared assemblies by measuring their deformation upon flow: hybrids with low lipid content behave like pure polymer vesicles, whereas objects mainly composed of lipids show more variability from one vesicle to the other. Finally, the structure of the nanosized assemblies is characterized through a combination of Dynamic Light Scattering, Small Angle Neutron Scattering and Transmission Electron Microscopy. A vesicles-to-wormlike transition has been evidenced due to the intimate mixing of DPPC and PBD-PEO at the nanoscale. Combining experimental results at the micron and at the nanoscale improves the fundamental understanding on the phase behavior of copolymer-lipid hybrid assemblies, which is a necessary prerequisite to tailor efficient copolymer-lipid hybrid devices

Control of the morphology of gold deposits grown at the gas/liquid interface

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Grafting of proteins onto polymeric surfaces: A synthesis and characterization challenge

This review aims at answering the following question: how can a researcher be sure to succeed in grafting a protein onto a polymer surface? Even if protein immobilization on solid supports has been used industrially for a long time, hence enabling natural enzymes to serve as a powerful tool, emergence of new supports such as polymeric surfaces for the development of so-called intelligent materials requires new approaches. In this review, we introduce the challenges in grafting protein on synthetic polymers, mainly because compared to hard surfaces, polymers may be sensitive to various aqueous media, depending on the pH or reductive molecules, or may exhibit state transitions with temperature. Then, the specificity of grafting on synthetic polymers due to difference of chemical functions availability or difference of physical properties are summarized. We present next the various available routes to covalently bond the protein onto the polymeric substrates considering the functional groups coming from the monomers used during polymerization reaction or post-modification of the surfaces. We also focus our review on a major concern of grafting protein, which is avoiding the potential loss of function of the immobilized protein. Meanwhile, this review considers the different methods of characterization used to determine the grafting efficiency but also the behavior of enzymes once grafted. We finally dedicate the last part of this review to industrial application and future prospective, considering the sustainable processes based on green chemistry